Planar Lighting Device with Varying LED Array Density
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Solution Overview
Problem
Current planar lighting devices face challenges in achieving a thinner design and larger dimensions while maintaining uniform light distribution and low power consumption, as they require thicker light guide plates and are limited by the size of light sources, leading to increased manufacturing costs and power consumption.
Innovation Solution
A planar lighting device with a light guide plate featuring a flat exit plane, inclined rear planes, and paired light sources with varying LED chip array densities and light amounts, allowing for efficient light distribution and reduced thickness, achieved through the use of LED chips with different light emission faces and scattering particles within the light guide plate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a direct illumination type backlight unit is used, then uniform light amount distribution is achieved, but the backlight unit thickness increases to about 30 mm
Solution Approach 1:
A light guide plate is introduced as an intermediary component between the light source and the display panel. The light guide plate receives light from the light source, guides it through its interior, and emits it uniformly across the display panel area, enabling thin backlight unit design while maintaining uniform illumination.
Solution Approach 2:
The light guide plate utilizes its thickness dimension to guide and distribute light. By designing the light guide plate with specific thickness variations and optical properties, the system achieves uniform light distribution across the display panel while keeping the overall backlight unit thickness minimal.
2Length of stationary object
If the backlight unit thickness is reduced to 10 mm or less, then a thinner design is achieved, but uniform light amount distribution becomes difficult to maintain
Solution Approach 1:
The light guide plate's optical parameters are optimized, including its refractive index, thickness profile, and scattering properties. By carefully controlling these parameters, the system achieves uniform light distribution even with reduced thickness of 10 mm or less.
Solution Approach 2:
The light guide plate is designed with non-uniform thickness and optical properties across different regions. The thickness varies locally to compensate for light loss and ensure uniform overall illumination, while maintaining a thin overall profile of 10 mm or less.
3Area of stationary object
If larger dimensions are achieved with light guide plates, then the light guide plate thickness must be increased, but this increases device complexity and manufacturing difficulty
Solution Approach 1:
The light guide plate is divided into multiple functional layers and regions, each optimized for specific light guiding and distribution tasks. This segmentation allows the system to achieve large dimensions while keeping individual component thicknesses manageable and simplifying manufacturing.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration enables a high-in-the-middle, bell-curve illuminance distribution without increasing the number of light sources or manufacturing costs, allowing for thinner and larger designs suitable for liquid crystal display devices like televisions.
Implementation Method 1
a light guide plate for admitting light emitted by the light sources and emitting the light through the light exit plane thereof
Implementation Method 2
light emitted by the light source and admitted through the light entrance plane into the light diffusion light guide member receives a single or a multiple scattering effect at a given rate as the light propagates through the inside of the light diffusion light guide member
Data Source
AI summary
A thinner and larger planar lighting device is achieved without increasing the number of light sources and holding the power consumption to a minimum. The LED chips on the light sources are arrayed at an array density varying according to the position of each of the light entrance planes of the light guide plate such that the illuminance distribution as measured on along the middle of the light guide plate in a direction parallel to longitudinal direction of the light entrance planes represents a high-in-the-middle, bell-curve distribution.